Machines with internal combustion burn their fuel in compressed atmospheric air and mix their combustion gases inherently with this air and the residual oxygen which is not utilized. In this process, the fuels, which are almost always carboniferous, produce, inter alia, CO.sub.2, which is considered to be a greenhouse gas. The common utilization of fossil fuels nowadays releases CO.sub.2 quantities which constitute a risk, discussed worldwide, to the global climate. An intensive search for CO.sub.2 -free technologies is therefore already under way.
Energy supply is nowadays determined by the utilization of fossil fuel energy in machines with internal combustion, the disposal of the highly diluted CO.sub.2 taking place into the atmosphere.
The CO.sub.2 separation from the exhaust gases with disposal by liquefaction, separation and sealing off from the atmosphere would be obvious. However, due to the large volumetric flows, such a plan cannot be put into practice.
A further known possibility is the recirculation of cooled-down exhaust gases into the intake of machines with internal combustion. This may take place to the extent that the oxygen of the air is just used up. In this case, however, the exhaust gas still remains mixed with the atmospheric nitrogen, and the CO.sub.2 separation problem is thus only marginally reduced.
Furthermore, all air-operated internal combustion engines also produce nitrogen oxides, which act as air pollutants and the generation of which is controlled by costly measures.